The present invention relates to a process for the production of fireproof or refractory (hereinafter referred to collectively as "refractory") shapes of ceramic fiber-containing material, wherein (a) a slurry of fireproof and/or refractory fibers (hereinafter referred to collectively as "refractory fibers") and fine-grained and/or finely divided, fireproof and/or refractory materials (hereinafter referred to collectively as "particulate refractory material") and optionally other additives is produced in water, (b) the particulate refractory material is flocculated on the fibers by means of a flocculant, and (c) the desired shape is produced by dewatering the slurry in a suitable mold that enables the water to be removed, followed by drying the shapes.
The invention also relates to the shapes produced in accordance with this process, as well as the use of these shapes.
A refractory, heat-insulating material is known from Accepted West German Specification (DE-AS) No. 19 47 904 produced from 10 to 97 parts by weight of a refractory fiber component and 1 to 20 parts by weight of a metal powder, using colloidal silicon dioxide sol and starch as binders. In this publication, it is recited that an aqueous slurry containing 1% solids is produced from these solid constituents, the slurry is subsequently dewatered in suitable sieve molds, and the resulting shape is dried at temperatures of 160.degree. C.
A fiber-reinforced board and a process for the production thereof are known from European Published Patent Application No. 0 077 444, wherein the fiber-reinforced board contains 15 to 40 parts by weight of ceramic fibers, 1 to 6 parts by weight of organic fibers, 1 to 6 parts by weight of an organic binder, 0 to 5 parts by weight of colloidal silicon dioxide, 0.2 to 2 parts by weight of a flocculant, and about 50 to 80 parts by weight of an inorganic, refractory filler. According to the process described in this publication, the organic fibers are first broken down in a grinding machine at a solids content of about 1 to 15 parts by weight in an aqueous slurry, whereupon the other constituents are added. It is indicated that the binder and the colloidal silicon dioxide are deposited on the fibers by the flocculant. Polyacrylamide, polyacrylimide and compounds producing polyvalent ions are disclosed as flocculants. Starch can be used as a binder.
Furthermore, a fibrous material is known from European Patent Application No. 0 073 854, for whose production fibers dispersed in water are first impregnated with a flocculant, then dried. An aqueous dispersion is then again produced from these impregnated dried fibers, which may also be inorganic fibers, with the addition of finely divided inorganic powders, and a board-like material is formed by a papermaking process. However, in this publication, it is expressly stated that the fiber length should preferably be greater than 0.5 mm, and most preferably greater than 1.5 mm.